Under Review False Level Up

Sometimes when I battle, my Doen's EXP bar will say he leveled up when he really didn't. This started happening after I added a new Pali (a Nimbi) to the squad. No stat points were gained when this happened. As far as I know, I have not seen this with any of my other Palis.
Here's Donn's stats, if they are needed: (Picture was taken right after the battle in the above picture)